NQE: Use cached estimates

net/nqe/network_qualities_prefs_manager.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_NQE_NETWORK_QUALITIES_PREFS_MANAGER_H_
 #define NET_NQE_NETWORK_QUALITIES_PREFS_MANAGER_H_
 
 #include <map>
 #include <memory>
 
@@ skipping 36 matching lines @@
     : public nqe::internal::NetworkQualityStore::NetworkQualitiesCacheObserver {
  public:
   // Provides an interface that must be implemented by the embedder.
   class NET_EXPORT PrefDelegate {
    public:
     virtual ~PrefDelegate() {}
 
     // Sets the persistent pref to the given value.
     virtual void SetDictionaryValue(const base::DictionaryValue& value) = 0;
 
-    // Returns the peristent prefs.
-    virtual const base::DictionaryValue& GetDictionaryValue() = 0;
+    // Returns a copy of the persistent prefs.
+    virtual std::unique_ptr<base::DictionaryValue> GetDictionaryValue() = 0;
   };
 
   // Creates an instance of the NetworkQualitiesPrefsManager. Ownership of
   // |pref_delegate| is taken by this class. Must be constructed on the pref
   // thread, and then moved to network thread.
   explicit NetworkQualitiesPrefsManager(
       std::unique_ptr<PrefDelegate> pref_delegate);
   ~NetworkQualitiesPrefsManager() override;
 
   // Initialize on the Network thread.
@@ skipping 46 matching lines @@
 
   // Used to get |weak_ptr_| to self on the pref thread.
   base::WeakPtrFactory<NetworkQualitiesPrefsManager> pref_weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(NetworkQualitiesPrefsManager);
 };
 
 }  // namespace net
 
 #endif  // NET_NQE_NETWORK_QUALITIES_PREFS_MANAGER_H_